Method of dewaxing petroleum products with monobromo-monochloromethane



Patented Dec. 18, 1951 METHOD OF DEWAXING PETROLEUM PROD- UCTS WITHMONOBROMO-MONOCHLORO- METHAN E Karl A. Fischer, College Park, Md.

No Drawing. Application November 10, 1949, Serial N0. 1 26,675

3 Claims. (01. 196-19) (Granted under the act of March 3, 1883, as

The invention described herein, if patented, may be manufactured andused by or for the Government for governmental purposes without thepayment to me of any royalty thereon.

This invention relates to an improvement in dewaxing petroleum productsand more particu larly to dewaxing lubricating oil distillates andraflinates with the agent monochloro-monopromo-methane.

The present day method of removing waxes from petroleum distillates andraiflnates comprise amended April 30, 1928; 370 0. G. 757) luting agentwhich is non-flammable and will the dilution of an oil with suitablesolvents or solvent combinations such as gasoline, esters, l etones,hydrocarbons such as benzene and toluene,

brominated hydrocarbons, chlorinated hydrocarbons, fluorinatedhydrocarbons, and many others. The principle of the method utilizingthese agents is to compose a diluting liquid which has the property ofbeing homogeneously miscible with oil at low temperature while itssolving leave much to be desired in simplifying and economizing dewaxingof petroleum products. Particularly, the adjustment of solvent couplesto the proper selectivity and the fire hazard which is involved in theuse of propane or benzene combinations is a considerable drawback.Further, the use of known chlorinated hydrocarbons frequently requiresmore chilling than is feasible or practical in many types of systemsbecause of their oftentimes undesirable solvent power for paraflinwaxes. In attempting to offset this solvent power by balancingchlorination to meet the requirements from the wax side, the danger ofphase separation occurring in the oil phase becomes a detrimentalproblem relative to obtaining oils of desired pour points.

It is therefore an object of this invention to provide an improved oildewaxing agent which simplifies the process of dewaxing petroleumproducts without danger of oil-phase separation.

It is another object of this invention to provide an improvement ineconomizing the process of dewaxing oils.

A further object of this invention is to provide an improved solventprocess for dewaxing lubricating oils, distillates and raflinates with adiserve to extinguish hydrocarbon fires.

Another object of this invention is to provide an improved dewaxingagent and process utilizing a monochloro-monobromo-methane solventdiluting agent in which the wax and oil are readily soluble at normaltemperatures and provides no pronounced selectivity to petroleumhydrocarbons at low dewaxing temperatures whereat the wax separates fromthe mixture.

Other objects and advantages will be apparent from the followingexamples.

Illustratively, for example, a petroleum railinate diluted with 200% pervolume of monochloro-monobromo-methane at normal room temperature andchilled to 20 C. releases the wax as physical bodies which partly floaton the surface of liquid mix due to the differences in specificgravities. The wax, in some cases, can be spray-washed by the dilutingagent and removed as in a flotation process which eliminates the usualfilters or centrifuges. However, in most cases where the wax content ishigh, better results in pour point values are obtained by use of aconventional filter or centrifuge process.

More specifically, to illustrate the results obtained by use ofmonochloro-monobromo-methane as a diluting solvent for dewaxinghydrocarbon oils, it was discovered that a refined heavy lubricating oilfrom Pennsylvania stock having a pour point of 20 C. when mixed with 1%paraifin, on a basis of weight measurement, and diluted with 200%monobromo-monochloro-methane per unit volume, at room temperature,chilled to 20 C. produced, when filtered, and twice washed with 25%additional monochloro-monobromo-methane, a lubricating oil with a newpour point of -21 C. upon evaporation of the diluting solvent. Theseparation of the solvent from the oil, after dewaxing, is by anyconventional means as heating to boil off the solvent.

In neither of the above processes was there any sign of oil phaseseparation at the dewaxing temperature of 20 C. and the wax appeared toseparate quantitatively.

In addition, this solvent may be used in combination with otherselective and non-selective solvents, of the characteristics heretoforeindicated, with or without inflammable characteristics, and, in additionto economizing on their use, provides a fire extinguishing actionagainst the inflammable hydrocarbons.

As heretofore mentioned some solvents as ketones, alcohols, esters,dichloromethane and certain other chlorinated hydrocarbons when used 3alone or in combination with other solvents cause a phase breakdown ofthe oil components at dewaxing temperatures. However, the pronouncedselectivity of such dilutents at low deto 100 oil parts provides at -20C., with convene-v tional centrifuging or filtering and conventionalremoval of solvents, a dewaxed oil of improved pour point value. Theprocess of dewaxing' the oil is simplified by the disregarded of oilphase 7 breakdown and the ease of wax separation facilitated at thedewaxing temperature of 20 C. or lower, if desired.

Having thus described the general mode of utilizingmonochloro-monobromo-methane in dewaxing petroleum products itwill'beapparent that the improvements provided thereby maybe applicableto processes fallingwithin the scope of 'my claims.

What 1 claim is:

1. A process of dewaxing oils, which comprises diluting an oil withmonochloro-r'nonobromo- 4 methane, chilling the mixture, and separatingthe wax.

2. A process of dewaxing petroleum products, which comprises subjectingthe petroleum to the action of monochloro-monobromo-methane incombination with a more selective solvent, chilling and separating thewax.

3. A process of dewaxing oil distillates and rafiinates, which comprisesdiluting the oil distillates and rafnnates withmonochloro-monobromo-methane in amounts constituting substantiallydouble to three times the volume of the oil content, chilling thediluted mixture until a substantially quantitative separation of the waxfrom oil constituents occurs, and separating the wax.

KARL A. FISCHER.

REFERENCES CITED The, following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,988,706 Swift Jan. 22, 19352,049,059 Goss et a1. July 28, 1936 2,129,752 Whiteley Sept. 13, 19382,137,218 Govers Nov. 15, 1938 2,162,682 Terres et a1 June 13, 1939

1. A PROCESS OF DEWAXING OILS, WHICH COMPRISES DILUTING AN OIL WITHMONOCHLORO-MONOBROMOMETHANE, CHILLING THE MIXTURE, AND SEPARATING THEWAX.